LOCATION ROTADO NMTentative Series
TAXONOMIC CLASS: Fine, mixed, superactive, mesic Typic Paleustalfs
TYPICAL PEDON: Rotado loam-on a summit of an interfluve sloping 5 percent to the south-southeast at 7,585 feet elevation-rangeland. (Colors are for dry soil unless otherwise noted. When described on September 7, 2000, the soil was dry throughout.)
Oi--0 to 1 inch; slightly decomposed needles, twigs, roots and leaves; abrupt smooth boundary
A--1 to 5 inches; brown (7.5YR 5/3) loam, brown (7.5YR 4/3) moist; weak fine granular structure; slightly hard, friable, slightly sticky and nonplastic; common fine and common very fine roots; common fine irregularly shaped pores; 2 percent paragravel; neutral (pH 6.6); clear smooth boundary. (2 to 4 inches thick)
E--5 to 11 inches; pinkish gray (7.5YR 6/2) loam, brown (7.5YR 4/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; few medium, common fine, and common very fine roots; common fine tubular pores; 2 percent paragravel; neutral (pH 6.6); clear smooth boundary. (5 to 16 inches thick)
EB--11 to 18 inches; light brown (7.5YR 6/3) loam, brown (7.5YR 5/4) moist; moderate medium subangular blocky structure; moderately hard, friable, slightly sticky and slightly plastic; few medium, few fine, and common very fine roots; few fine and common very fine tubular pores; 2 percent paragravel; neutral (pH 6.6); clear smooth boundary. (5 to 9 inches thick)
2Bt--18 to 28 inches; yellowish red (5YR 5/6) clay, yellowish red (5YR 4/6) moist; strong coarse angular blocky parting to strong fine subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common medium, few fine, and few very fine roots; few fine tubular pores; many prominent clay films on faces of peds; 10 percent paragravel; neutral (pH 6.8); clear wavy boundary. (10 to 22 inches thick)
2Crt--28 to 38 inches; moderately cemented rhyolitic tuff bedrock (Bandelier Tuff formation)
TYPE LOCATION: Bandelier National Monument, Los Alamos County, New Mexico; USGS Frijoles 7.5 minute topographic quadrangle; about 5 miles southwest of Los Alamos; 35 degrees, 48 minutes 47.31 seconds N and 106 degrees 24 minutes, 45.06 seconds W, NAD 27.
RANGE IN CHARACTERISTICS: (Depths given are measured from the mineral surface)
Soil moisture - The soil moisture control section (SMCS) is moist in all parts from January to May and intermittently moist in some part from June to December. The SMCS is dry in some part 40 to 60 percent of the time when the soil temperature at 20 inches is above 41 degrees F. The soil moisture regime is typic ustic.
Average annual soil temperature: 47 to 49 degrees F
Depth to base of albic horizon: 8 to 15 inches (20 to 38 cm)
Depth to paralithic contact: 25 to 39 inches
Lithology of pararock fragments: Rhyolitic tuff
Volcanic glass content in the upper part: 10 to 20 percent in the coarse silt plus sand fraction
Particle-size control section weighted averages:
Silicate clay content: 40 to 60 percent
Sand content: 15 to 35 percent
Fine sand or coarser content: 5 to 25 percent
Pararock fragment content: 0 to 5 percent paragravel
A horizon
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 to 4 moist
Chroma: 2 or 3, dry or moist
Clay content: 14 to 24 percent
E horizon
Hue: 7.5YR or 10YR
Value: 5 to 7 dry, 4 or 5 moist
Chroma: 1 or 2, dry or moist
Clay content: 16 to 24 percent
EB horizon
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 3 to 5 moist
Chroma: 2 or 3 dry, 2 to 4 moist
Clay content: 14 to 24 percent
Pararock fragments: 0 to 2 percent paragravel
2Bt horizon
Hue: 5YR to 10YR
Value: 4 to 6 dry, 3 or 4 moist
Chroma: 4 or 6, dry or moist
Clay content: 40 to 60 percent
Pararock fragments: 5 to 14 percent paragravel
COMPETING SERIES: There are no competing series in this family. A similar soil in another family is the Predawn series. Predawn soils are fine-loamy, very deep, and have strong calcic horizons.
GEOGRAPHIC SETTING: Rotado soils are on summits of interfluves on undulating plateaus. They formed in eolian material over residuum derived from rhyolitic tuff of the Quaternary Age Bandelier Tuff formation. Slopes are 2 to 8 percent. Elevation ranges from 6,900 to 7,600 feet. The mean annual precipitation is 16 to 20 inches with about 45 percent falling as rain from high-intensity convective thunderstorms between July and September. The mean annual air temperature is 45 to 47 degrees F. The frost-free period is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Adornado, Letrado, Tocal, and Urioste soils. Adornado soils are ashy-pumiceous, have mollic epipedons, and occur on backslopes and footslopes of interfluves. Letrado soils are fine-loamy, very deep, and occur on toeslopes of interfluves. Tocal soils are clayey, shallow, and occur on shoulders of interfluves. Urioste soils are ashy, very shallow, and occur on backslopes of interfluves.
DRAINAGE AND PERMEABILITY: Well drained; high runoff; permeability is slow.
USE AND VEGETATION: Rotado soils are used for recreation and wildlife. Present vegetation is little bluestem, threeawn, mountain muhly, western wheatgrass, sideoats grama, buckbrush, and scattered ponderosa pine
DISTRIBUTION AND EXTENT: Rotado soils are of small extent on the southwestern Jemez Volcanic Field part of the Southern Rocky Mountain province in northcentral New Mexico. The MLRA is 48A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Los Alamos County, New Mexico; Bandelier National Monument Soil Survey, 2000. Rotado is a coined name.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 1 to 5 inches (A horizon)
Abrupt textural change and Pale- feature - The increase of 20 percent clay with a clear boundary at 18 inches. (EB to 2Bt horizons)
Albic horizon - from 5 to 11 inches (E horizon)
Argillic horizon - The zone from 18 to 28 inches (2Bt horizon)
Paralithic contact - Moderately cemented rhyolitic tuff bedrock at 28 inches (2Crt layer)
Particle-size control section - The zone from 18 to 28 inches (2Bt horizon)
Classified according to Soil Taxonomy Second Edition, 1999.